src/filters.py

   1 """Image filters module.
   2
   3 All filters return a filtered copy of the image, the original image is
   4 preserved.
   5 """
   6
   7 from PIL import Image, ImageFilter
   8 import numpy as np
   9
  10 import pcf
  11
  12 def color_enhance(image):
  13     """Stretch all color channels to their full range."""
  14     image_l = image.load()
  15     min_r, min_g, min_b = 999, 999, 999
  16     max_r, max_g, max_b = -1, -1, -1
  17
  18     for x in xrange(image.size[0]):
  19         for y in xrange(image.size[1]):
  20             min_r = min(min_r, image_l[x, y][0])
  21             max_r = max(max_r, image_l[x, y][0])
  22             min_g = min(min_g, image_l[x, y][1])
  23             max_g = max(max_g, image_l[x, y][1])
  24             min_b = min(min_b, image_l[x, y][2])
  25             max_b = max(max_b, image_l[x, y][2])
  26
  27     new_image = Image.new('RGB', image.size)
  28     new_image_l = new_image.load()
  29     for x in xrange(image.size[0]):
  30         for y in xrange(image.size[1]):
  31             r, g, b = image_l[x, y]
  32             r = (r - min_r) * 255 / (max_r - min_r)
  33             g = (g - min_g) * 255 / (max_g - min_g)
  34             b = (b - min_b) * 255 / (max_b - min_b)
  35             new_image_l[x, y] = (r, g, b)
  36
  37     return new_image
  38
  39 def edge_detection(image):
  40     """Edge detection (on BW images)."""
  41     new_image = image.filter(ImageFilter.GaussianBlur())
  42     # GaussianBlur is undocumented class, it might not work in future versions
  43     # of PIL
  44     new_image = Image.fromstring('L', image.size,
  45                              pcf.edge(image.size, image.tostring()))
  46     return new_image
  47
  48 def peaks(image):
  49     """Peak filter (on BW images)."""
  50     image_l = image.load()
  51     new_image = Image.new('L', image.size)
  52     new_image_l = new_image.load()
  53     for x in range(2, image.size[0] - 2):
  54         for y in range(2, image.size[1] - 2):
  55             pix = (sum([sum([
  56                 - image_l[a, b]
  57                     for b in range(y - 2, y + 3)])
  58                     for a in range(x - 2, x + 3)])
  59                 + (17 * image_l[x, y]))
  60             if pix > 255:
  61                 pix = 255
  62             if pix < 0:
  63                 pix = 0
  64             new_image_l[x, y] = pix
  65     return new_image
  66
  67 def high_pass(image, height):
  68     """High pass filter (on BW images)."""
  69     image_l = image.load()
  70     new_image = Image.new('L', image.size)
  71     new_image_l = new_image.load()
  72
  73     for x in xrange(image.size[0]):
  74         for y in xrange(image.size[1]):
  75             if image_l[x, y] < height:
  76                 new_image_l[x, y] = 0
  77             else:
  78                 new_image_l[x, y] = image_l[x, y]
  79
  80     return new_image
  81
  82 def components(image, diameter):
  83     # TODO comment
  84     # TODO refactor
  85     image_l = image.load()
  86     new_image_l = np.zeros(image.size, dtype=np.int)
  87
  88     components = [None]
  89     comp_counter = 1
  90
  91     if diameter == 1:
  92         for y in xrange(1, image.size[1] - 1):
  93             for x in xrange(1, image.size[0] - 1):
  94                 if image_l[x, y]:
  95                     s = {0}
  96                     s.add(new_image_l[x - 1, y - 1])
  97                     s.add(new_image_l[x, y - 1])
  98                     s.add(new_image_l[x + 1, y - 1])
  99                     s.add(new_image_l[x - 1, y])
 100                     if len(s) == 1:
 101                         components.append(set())
 102                         new_image_l[x, y] = comp_counter
 103                         components[comp_counter].add((x, y))
 104                         comp_counter += 1
 105                     elif len(s) == 2:
 106                         s.remove(0)
 107                         c = s.pop()
 108                         new_image_l[x, y] = c
 109                         components[c].add((x, y))
 110                     else:
 111                         s.remove(0)
 112                         c1, c2 = s.pop(), s.pop()
 113                         components[c2].add((x, y))
 114                         for (x1, y1) in components[c2]:
 115                             new_image_l[x1, y1] = c1
 116                         components[c1] = components[c1] | components[c2]
 117                         components[c2] = None
 118     elif diameter == 2:
 119         for y in xrange(2, image.size[1] - 2):
 120             for x in xrange(2, image.size[0] - 2):
 121                 if image_l[x, y]:
 122
 123                     s = {0}
 124                     for (a, b) in [(a,b) for a in range(x - 2, x + 3)
 125                               for b in range(y - 2, y + 1)]:
 126                         if not (b == y and a >= x):
 127                             s.add(new_image_l[a, b])
 128
 129                     if len(s) == 1:
 130                         components.append(set())
 131                         new_image_l[x, y] = comp_counter
 132                         components[comp_counter].add((x, y))
 133                         comp_counter += 1
 134                     elif len(s) == 2:
 135                         s.remove(0)
 136                         c = s.pop()
 137                         new_image_l[x, y] = c
 138                         try:
 139                             components[c].add((x, y))
 140                         except AttributeError:
 141                             print s, c
 142                             raise AttributeError
 143                     else:
 144                         s.remove(0)
 145                         c1 = s.pop()
 146                         components[c1].add((x, y))
 147                         new_image_l[x, y] = c1
 148                         for c2 in s:
 149                             for (x1, y1) in components[c2]:
 150                                 new_image_l[x1, y1] = c1
 151                             components[c1] = components[c1] | components[c2]
 152                             components[c2] = None
 153     else:
 154         pass #TODO error
 155
 156
 157     new_image = Image.new('L', image.size)
 158     new_image_l = new_image.load()
 159
 160     for component in components:
 161         if component:
 162             x_c = 0
 163             y_c = 0
 164             c = 0
 165             for (x, y) in component:
 166                 x_c += x
 167                 y_c += y
 168                 c += 1
 169             new_image_l[int(round(float(x_c)/c)), int(round(float(y_c)/c))] = 255
 170
 171     return new_image
 172